


An Alliance for the Ages

by RedOrchid



Series: Sliding Doors [3]
Category: Shadowhunters (TV)
Genre: Alliance Rune (Shadowhunter Chronicles), Canon Divergence, Established Relationship, Future Fic, Garroway/Fray family lives on happily in the background, Happy Ending, Happy Sex, Jocelyn Is Alive, Love, M/M, Marriage Proposal, Porn with Feelings, Sex Magic, Soul Bond, so much love
Language: English
Status: Completed
Published: 2017-08-04
Updated: 2017-08-04
Packaged: 2018-12-11 01:23:29
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,749
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11703867
Author URL: https://archiveofourown.org/users/RedOrchid/pseuds/RedOrchid
Summary: He feels the connection light up almost instantly, a familiar pressure deep in his gut coming to life and spreading like wildfire through his bloodstream. They gasp into each other’s mouths as Alec’s hands find their way beneath the edge of Magnus’ shirt, his fingers dancing over taut skin, and then moving lower, dipping into the waistband of Magnus’ pants.Clary discovers the Alliance Rune; Magnus and Alec are the first couple to try it out.





	An Alliance for the Ages

**Author's Note:**

> Future!fic, canon-divergent. (Jocelyn is alive, Clary calls Luke ‘dad’, Alec and Magnus have a small magic problem where their souls try to marry each other whenever they have sex, everything else’s business as usual.) 
> 
> (If you’re reading this as part of [the Sliding Doors series](http://archiveofourown.org/series/524512), this fic takes place ca six months after the end of [Closed Doors Don’t Lie](http://archiveofourown.org/works/7715878/chapters/17584204).)

“So, wait, you’re saying that this rune you had a vision of, it’ll bind our essences together?” Alec asks. “Letting us share our powers?”

At his side, Magnus grabs hold of his arm, then slides his hand down it to weave their fingers tightly together. Alec leans into it on instinct, his own fingers squeezing Magnus’ in reply. His heart is beating a lot faster, all of a sudden.

“Yeah. I mean, that’s what I saw, at least?” Clary replies, a big smile on her face as she holds up a drawing of a rune Alec’s never seen before. “Look, in my vision this half was drawn on the Downworlders, and this half on the Shadowhunters. And then the Downworlders were wielding seraph blades, and the Shadowhunters were having vamp speed and taking wolf form and doing all kinds of magic. I’m trying it out on mom and dad later tonight.”

Alec swallows, his mind spinning with implications of what this could mean. For the war; for bridging the gaps between factions; for the Clave’s outdated and prejudiced ways.

For him and Magnus, and their relationship.

“How long does it last?”

“Not 100% sure,” Clary replies. “I kind of got the feeling it’s pretty permanent.”

“So, like a magical marriage?” Magnus adds, as he takes out his phone to take a picture, putting into words exactly what Alec was thinking.

“Or any other kind of life-long connection, which is why I’m thinking of calling it the Alliance rune,” Clary says. “I mean, I’m binding myself to Simon because he’s always been my best friend.”

Alec shares a quick look with Magnus, seeing the same flicker of surprise mirrored in his eyes. “Um. How’s Jace taking that?”

For a split moment, Clary seems to stiffen and hesitate. But then she shrugs instead, and the smile comes back to her face.

“Actually, he’s thinking of asking Maia. I mean, I know they both like to pretend that they still hate each other, but they’ve become really good friends. Last night, they were watching date movies together and throwing popcorn on the TV and yelling ‘Jace moment!’ or ‘Maia moment!’ whenever one of the characters made bad relationship choices.”

Alec snorts. “I’m guessing there was a lot of yelling in that case.”

“Oh, pretty much constant,” Clary replies, her feet clearly back under her. “They also have this thing when they try to one-up each other about bad things that have happened to them in the past. I don’t really get it, but it seems to be helping both of them deal, so… I don’t know. I think they’d make a good team.”

“They certainly have that straight-forward, surge-into-battle-while-throwing-quips thing in common,” Magnus remarks, and then he turns his attention to Alec. “Alexander, can I talk to you alone for a moment?”

“Yeah, sure,” Alec replies, feeling his brow crease at the sudden seriousness of Magnus’ face. He turns and gestures towards the open glass doors behind them. “Out there, or?”

“Somewhere a bit more private, I think,” Magnus replies. “Biscuit, if you’ll excuse us?”

“Don’t worry about it, I completely understand,” Clary says, folding up her drawing and putting it back into her bag. “It’s a big step. Take your time. Actually, I’m going to go meet Jace for dinner. Call me when you’ve talked it over, okay?”

“Will do,” Magnus tells her. “And, Clary, I don’t think we need to tell you to please be  _ very _ careful about who you share this information with?”

“No one outside of the immediate circle,” Clary confirms. “I already got the speech from dad. Speaking of, he asked you, Alec, to give him a call when you have a minute. Something about a potential turf war with a new pack in New Jersey?”

“Yeah, sure, I’ll get back to him on that in a day or so,” Alec replies, his mind automatically jumping over into work mode for a minute, before a light pressure around his hands pulls his focus back to Magnus and the situation at hand. “Go see Jace. We’ll call you later.”

Once she’s out the door, and they’re alone in the loft again, Magnus walks them both over to the couch and motions for Alec to take a seat.

“Well, that was certainly interesting,” he says, flicking his fingers and making a pair of crystal tumblers appear on the table in front of them. “I’m having a Whiskey Sour. What would you like?”

Alec shrugs. “That blackberry and vanilla vodka thing you made last night was good. I’ll have that again, if we didn’t use all the blackberries that were left for breakfast this morning.”

“I think there’s still a few left,” Magnus replies, and then sends a spark of magic into the air. A few different bottles appear, along with the berries, lemons, and Magnus’ bartender equipment. Alec takes a moment to relax back against the couch, watching Magnus’ hands as he prepares their drinks.

“So, I guess it’s safe to say that neither of us saw that coming,” Magnus says, after handing Alec his drink. “Shadowhunters and Downworlders sharing each other’s powers. That’s a political powder keg, if I ever saw one.”

“Yeah, no kidding,” Alec agrees. “What do we do about it?”

“Ever since Valentine and that little sneaky blond helper of his broke out all those demons from their hell realms, every part of the shadow world is fighting a losing battle,” Magnus says with a sigh. “We all know it, even if it hasn’t gotten to the point yet where everyone is willing to put their past grievances aside and actually work together.”

“And you think that Clary’s vision means we all need to step up our game?”

“If Ithuriel sent it to her, then yes, I do. I’m not sure what Valentine is planning next, but looking at his track record in the past six months, I shudder to think what he’s got in store for us.”

Alec runs a number of different scenarios in his head, and ends up wincing.

“One thing’s for sure: one way or the other, if the power of this rune truly runs both ways between the allied parties, it has the potential to completely wreck the status quo,” Magnus continues. “It could re-write the political structure of the entire Shadow World. Lines in the sand that have been relatively undisturbed for millennia just… wiped clean.”

“It would put Downworlders and Shadowhunters on equal footing, powerwise,” Alec agrees. “Unless it requires a Shadowhunter to activate the bond every time it’s used. If that’s the case then…”

“... the Clave would essentially have a weapon on their hands to enslave the rest of us by taking all the powers of the Downworld for themselves,” Magnus finishes for him.

There is heavy silence for a while, each of them lost in thought. Alec takes a long drink of his cocktail, looking at Magnus over the rim of his glass. In the months they’ve been together, he’s seen Magnus at his best and his worst; powerful and powerless; without a care in the world and looking like he carries the weight of thousands on his shoulders.

In the past few months it’s been rare to see him as quiet and contemplative as Alec is seeing him now. It both unnerves him and gives a special tug at his heart.

“So what do we do?” he says, once the silence has gone on for long enough.

Magnus looks at him intently. Then he puts his glass to his lips and throws the rest of his drink back in one go. “We test it out. Here. You and me. Tonight.”

Alec frowns “Won’t that risk being a little, you know—”

“Reckless? Oh, most definitely.”

“I was going to say ‘inconclusive’,” Alec replies. “I mean, we’re not really your run-of-the-mill Downworlder-Shadowhunter pair.”

He reaches out and takes Magnus’ hand in his, then pushes back the sleeve of Magnus’ jacket with the tips of his fingers, revealing the thin gold bracelet that wraps around his boyfriend’s wrist. As he slides his hand over it, he can feel Magnus magic surge up towards him, pooling right beneath Magnus’ skin and making the bracelet glow bright as it keeps the magic from spilling over and seeping into Alec’s skin.

There’s a small spark of green as Alec’s own energy reaches out in response, and Alec takes a moment to revel in the intimacy of the half-formed bond that already exists between him and Magnus—which has only grown stronger over the six months that have passed since they first got together.

Magnus smiles, almost to himself, as he looks down at their hands. “I don’t think it’ll have any negative effect, but let’s go into the study, just to be safe. We’ll have more space there—not to mention that the walls are strengthened to withstand any magical accidents that may occur.”

He pushes himself off the couch, pulling lightly at Alec’s hand. “You coming?”

Alec follows his lead, walking with Magnus through the loft and into the room where Magnus normally practices his magic. It’s cluttered with tables and brewing equipment from a batch of potions Magnus was making earlier, so Alec stops right inside the doors, keeping out of the way as Magnus pushes everything up against the walls with a sweep of his arm.

Once the floor is free, he turns to Alec. “There. Are you ready to do this?”

Alec nods, stepping forward—and then a thought that has been on his mind more often than not in the past couple of months pops to the surface, leaving him with a sudden, desperate sense of urgency.

“Wait, Magnus, there’s something we need to talk about first.”

“Alexander, we don’t have a lot of time,” Magnus replies. “If we’re going to do this before Clary tries it on either herself or Jocelyn and Luke, we need to—” 

“We have time for this,” Alec interrupts him, and then he reaches into his pocket, feeling for the small bag he knows is there while lowering himself down to one knee.

“I’ve been carrying this around with me, waiting for the right time to ask you for a long time now,” he says, taking the ring he bought weeks and weeks ago out of its bag and holding it up between them. “I know this isn’t the perfect setting—there’s no fancy dinner, or romantic sunset, or any of the other things I was trying to choose between—but that doesn’t change how sure I am. Of me, of us, of the fact that I want to share everything I am with you, for as long as I live.”

He reaches out an unsteady hand, relief flooding him as Magnus takes it. Magnus’ face is a study in shock, his free hand clasped over his mouth.

“Magnus Bane, will you marry me?”

Magnus makes a choked sound in his throat and pulls his hand out of Alec’s. For a terrible moment, Alec thinks he got it wrong—that Magnus isn’t on the same page, isn’t ready for them to take this step. But then Magnus is nodding furiously and pulling the rings he’s already wearing off his left hand, then holding it back out to Alec, who almost drops the ring he’s holding in his hurry to push it onto Magnus’ finger.

He surges back up, feeling Magnus’ magic come out and pull him the rest of the way to his feet. And then they’re kissing, deep and wet and with both of them shaking with emotion, clinging to each other to try and get as close as physically possible.

“So, that’s a yes?”

Magnus laughs into their kiss. “ _ Definitely _ yes.”

“Are you sure? I mean, absolutely sure?”

“I am,” Magnus replies, with absolute conviction. He catches Alec’s lips for another kiss and then pulls back a little to rest their foreheads together. “Are you?”

“Yes,” Alec says immediately. “Magnus, I love you. I want to do everything with you; I trust you with my life.”

“And I mine with yours,” Magnus replies. “Come on, then. Let’s see what this Alliance Rune is good for.”

Alec needs a moment to pull himself out of the euphoria that comes from the mind-boggling thought that  _ he and Magnus are going to get married _ , before he’s able to focus on the task at hand. It takes another couple of breathless kisses, as well as some groping that leaves both of them groaning and adjusting themselves before they succeed in taking their hands off each other—but they eventually manage to get there.

From the way Magnus is looking back at him, Alec is seriously proud of their self-control.

“Later,” he says, stopping himself at the last moment from reaching out and pulling Magnus back into his arms. His voice comes out hoarse and affected. He clears his throat and tries again. “We’ll—later. We’ll celebrate later.”

Magnus nods in agreement, and takes a long, steadying breath. He reaches into his pocket and takes out his phone, pulling up the picture he took of Clary’s drawing and handing it over to Alec.  

Alec takes out his stele and looks down at the photo of the rune, studying the lines of it to figure out how it’s meant to be drawn.

“I’m guessing I should draw on us both?” he says, looking back at Magnus for confirmation. “I mean, the stele’s adamas won’t work for you, so unless you draw yours with magic, then—”

He breaks off with a frown; next to him, Magnus has gone very still, a blank, almost guilty look settling on his face.

“Magnus, what’s wrong?”

Magnus visibly swallows, and then ducks his head, breaking eye contact. Alec waits, worry starting up in his gut and growing quickly as Magnus takes a step back, away from him.

“Magnus, talk to me,” he tries, as Magnus moves further away and starts pacing. “Did I say something wrong? I’m sorry if I—”

“No, it’s not you,” Magnus interrupts him, finally looking up to meet Alec’s eye. “It’s something about me that I—” He breaks off, pressing his lips tightly together before continuing, “It’s something I should have told you a long time ago. I just haven’t figured out how to actually do it.”

“So tell me now.”

“It’s not something you just  _ tell _ someone,” Magnus replies, sounding frustrated with himself. “It has to do with my past. And I know I’ve told you some really bad things. But this… it’ll change the way you look at me.”

“Hey,” Alec says, reaching out a hand to touch the side of Magnus’ face. “Remember when you told me about your worst memory?” he asks. Magnus swallows thickly, but manages a nod. “I meant what I said then; there’s nothing ugly about you, so whatever it is… we’ll deal with it. Together. Okay?”

Magnus looks at him for a long time, and Alec sees the conflict in his eyes. Whatever it is Magnus is struggling to tell him, it’s clearly something pretty big.

“Magnus,” he tries again, “you know you don’t have to tell me, right? Your past is your past. And whatever you’ll share with me, I’ll happily accept, but you don’t have to feel like you have to just because we’re, you know…” He can’t stop the smile that spreads on his face as he lets his hand drop, seeking out Magnus’ left one and bringing it to his lips.

He presses a kiss to the ring that now sits on Magnus’ fourth finger, and feels pure happiness surge through him once more. Magnus is is going to marry him.  _ Him _ . Whatever dark secrets are still hidden in his past, Alec really couldn’t care less at the moment; he feels like his feet might never come back to touch the ground again.

“I love you,” Magnus tells him, and Alec’s heart does another flip. “I love you, and I trust you. And I want you to know me, warts and all, so—” He breaks off, pulling his hand gently away from Alec’s hold. “Hand me your stele?”

“What?”

“Hand me your stele,” Magnus repeats.

Alec frowns, but does as told. The stele lies innocently in his hand for a moment, and then Magnus’ fingers close around it, his eyes fall closed, and Alec sees his brow furrow in concentration.

The stele activates, lighting up the room in a brilliant red colour.

Alec can’t contain his gasp. It should be impossible, and yet, the evidence that it’s clearly not is right in front of his eyes.

“How?” he manages, looking up at Magnus in shock? “How is that possible? Are you—“

“Secretly part Shadowhunter?” Magnus fills in for him. “No.”

“So then  _ how _ ?”

“I was fathered by Asmodeus,” Magnus replies. “A greater demon, but also—” he hesitates, then pushes forward, “—a fallen angel.”

Alec swallows hard, unsure of what to say. “Oh. Wow, um, that’s—”

“Yeah,” Magnus agrees, quietly. “Not really something that comes up naturally in a conversation.”

“So what does it mean? In terms of power?”

“I don’t know,” Magnus replies, simply. “I haven’t done extensive research on it. I know I can use adamas to some extent; It’ll light up red instead of white, but it’ll kill demons just the same. I can use a witchlight too. Beyond that… I don’t know.”

He looks down on the stele in his hand, and the red light fades. He hands the stele back to Alec.

“I’m sorry to spring this on you right now; if you want some time to think, I’ll understand.”

“What? No.” Alec reaches for him again, pulling Magnus’ eyes back to his with a light touch on his arm. “Magnus, I’m not going anywhere.”

“Alec, I’m a direct descendant of a greater demon. One of the princes of hell.”

“You’re also the best, kindest man I’ve ever met. What blood you have doesn’t change that.”

Magnus huffs and looks away, shaking his head. “You’re really intent on taking noble to a whole new level, aren’t you?”

“Well, if you’re going to be a butthead about it, then yeah, maybe I am,” Alec throws back, frustration rising up inside of him.

That shocks a laugh out of Magnus, and when he looks back up, his eyes are filled to the brim with conflicting emotion. “I’m a what, now?”

“You’re a butthead,” Alec repeats, crossing his arms over his chest for a moment, before letting them drop again with a sigh. “But you’re  _ my _ butthead. And I’m in this with you. So don’t... push me away.”

He locks his eyes with Magnus’, searching for a sign that Magnus understands what he’s saying, and, more importantly, that Magnus can convince himself to believe it. Magnus stares back at him for a long moment, a myriad of emotions playing across his face.

Alec waits, his breathing falling into sync with Magnus’ as they keep standing there, close enough to touch. He sees Magnus swallow hard, his adam’s apple working up and down his throat, and the next thing Alec’s knows, Magnus’ eyes are turning a brilliant gold.

There’s a faint  _ clang _ as the bracelets Magnus wears fall to the floor, and Alec gasps as he feels Magnus’ magic surge towards him. It halts just before making contact with Alec’s skin, and Alec can feel it wrap itself around them, energy suspended in the air, thick enough for him to almost grasp it in his hand, should he try to reach out and touch.

He meets Magnus eyes, and sees the question there. They haven’t talked about their could-be bond in quite some time, pushing it into the background like the proverbial elephant in the room by silent, mutual agreement once they managed to iron out the kinks that came with finding ways to work around it. Alec wets his lips as he thinks back on their first few times in bed together—how everything was on swirling and on edge for him, his body and soul desperately searching for a deeper connection.

He and Magnus found that in each other anyway—that and  _ so much more _ . And that makes what seemed like a natural progression to Alec a few months back a lot more scary. What they’ve created together is better than any fantasy Alec’s ever had, and even though he doesn’t like to think about it, his only frame of reference when it comes to soulbonds is the one he has with Jace.

And as much as he loves his  _ parabatai _ , there’ll always be an emotional distance between them  _ because _ of their bond, and the way it made several years of Alec’s youth incredibly difficult.

Almost as soon as the doubt bubbles up, he pushes it away again, ashamed of himself for even allowing it to surface to begin with. He just proposed, for the angel’s sake; and if there’s one thing he knows in his life, it’s that Magnus is who he wants to be with—completely and without reserve. And while the “without reserve” part may be scary, but there’s another feeling coming to the forefront that’s quickly overcoming that fear and helping pull Alec back to his senses.

_ Home _ . 

He reaches out to pull Magnus to him, needing him closer as he feels his own energy begin to respond to the magic surrounding them. Magnus dodges his grip, getting a firm hold on both of Alec’s hands instead and positioning them between their bodies.

“This is forever,” Magnus reminds him quietly, his grip on Alec’s hands warm and slightly trembling. “If we let this happen, there’s no turning back.”

“I know,” Alec replies, his breath quickening in his chest. “I’m ready. If you are, too?”

“I am.” An absolutely beautiful smile spreads across Magnus’ face as he lets go of Alec’s hands, taking a step closer and sliding his palms up to rest on Alec’s chest instead. “Come here and kiss me?”

Alec doesn’t hesitate. His own hands go to Magnus’ stomach, stroking lightly over the hard lines of his abs as he leans in and captures Magnus’ mouth with his.

He feels the connection light up almost instantly, a familiar pressure deep in his gut coming to life and spreading like wildfire through his bloodstream. They gasp into each other’s mouths as Alec’s hands find their way beneath the edge of Magnus’ shirt, his fingers dancing over taut skin, and then moving lower, dipping into the waistband of Magnus’ pants. 

They break the kiss and lean their foreheads together, both closing their eyes and fighting for air as the edges of the half-formed bond finally connects. Tendrils of Magnus’ magic seep into Alec and curl themselves around the wisps of Alec’s own essence that floats up to meet it. He feels warm all the way down to his bones, every part of him connected to the beautiful man in front of him.

He’s been in direct contact with Magnus’ magic numerous times by now: sharing strength; healing each other’s wounds after battle; the little sparks of everyday domesticity that mark their days around the loft, with books appearing in his hands when Alec wants them, coffee forming out of thin air in the mornings, and the loft itself generally being far more accommodating than any non-sentient space has the right to be.

It all pales in comparison to feeling Magnus’ magic fully connect. He’s used to sharp pulls of energy and the feeling of recklessly falling into something dangerous, but so good, he’ll gladly take the burn if he can just have it for a few more seconds. What he gets now, by contrast, is slow and sweet, and absolutely, unequivocally  _ thorough _ . He can feel Magnus down to the most fundamental level of his being, inside every muscle, every vessel—carving out a place for itself inside Alec’s very bones. And it still doesn’t feel anything like an intrusion; instead, it leaves him with a bone-deep sense of peace and happiness, and a deep, burning need to get even closer to Magnus than he already is.

He moves his fingers on impulse, twisting them like he’s seen Magnus do a hundred times before, and an almost dizzying thrill runs through him as Magnus lets out a surprised moan and almost doubles over, a familiar blue spark of magic seeping through his skin and moving into Alec’s hands, popping open the first two buttons of Magnus’ shirt as it goes.

When Magnus meets his eyes again, they’re a bright, molten gold, and Alec feels a new surge of energy as Magnus’ magic pulls him in completely, their lips meeting again in a deep, hungry kiss.

It’s like tide and ebb all at once, the essence from each of them flowing freely back and forth along their bond, until finding a perfect balance in the middle. Alec takes Magnus’ lips for yet another kiss, losing himself in the intimacy of their connection. Magnus’ fingers go the the hem of his shirt, pulling it up and over Alec’s head, and then slide down to his right flank, tracing the lines of his stamina rune.

The moan that breaks from Alec’s lips is swallowed up by the next kiss, hotter and more desperate than the ones before it, as Magnus’ uses their bond to pull Alec’s angelic powers forward, making the rune burn against Alec’s skin as it activates.

“Stamina, huh?” Alec manages, even as his own hands go to the front of Magnus’ shirt, bringing Magnus’ magic towards him and and making Magnus’ shirt open fully and move out of the way. “What happened to being pressed for time?”

Magnus stiffens against him, and then pushes them apart with a groan that sounds practically painful. “ _ Damn it _ . Why did you have to remind me of that?”

“Sorry,” Alec replies breathlessly, wrapping his arms around Magnus and pulling him close again. “I take it back. Come here; I need you inside of me. Right now.”

Magnus makes another pained sound, but instead of moving closer, he twists himself free of Alec’s hold and takes a number of steps back, leaving them both panting, staring at each other from across the room.

“Alexander,” Magnus says, and his voice is so thick with desire, it takes every bit of Alec’s self control not to cross the floor and go to him. “Remember what you said.” He wets his lips, eyes darting from Alec’s eyes down to his mouth for a second. “We’ll celebrate later. We waited half a year for this; we can make it another half an hour.”

“Speak for yourself,” Alec replies, but then closes his eyes and takes a deep breath to steady himself. “Okay, yeah, you’re right. Let’s test this rune and get it over with.”

“Couldn’t agree more,” Magnus says. He pulls his phone back out of his pocket for the second time and swipes the screen until he’s got the picture he’s looking for. “I still think you should draw both parts. Even if I’m able to get the adamas to light up, who knows what little twists and turns my heritage would bring to the magic.”

“Right,” Alec says, swallowing hard as he pulls his stele out of his pocket. He looks down at the screen of Magnus’ phone, studying the lines of the rune again. “She said this part was for the Shadowhunters, right?”

Magnus nods. “That one, yes.”

“Okay, then I’ll do the other part on you first,” Alec says, turning the stele over in his hand and lighting up the adamas at its core. “Where do you want it?”

“Here,” Magnus says, without hesitation, indicating the inside of his wrist.

Alec swallows. “That’s the spot Shadowhunters traditionally keep for the Wedded Union rune.”

“I know,” Magnus replies softly. “You still sure you want to do this?”

Alec looks back at him, taking in the flicker of doubt in Magnus’ eyes and feeling his own heart swell to the point of bursting all over again.

“Yeah,” he says, taking a step closer and curling his fingers around Magnus’ wrist. “I’m very, very sure.”

“Then get to it.”

Alec nods and turns Magnus’ wrist towards him. Magnus hisses in pain as the lines of the rune burn into his skin, and Alec winces, drawing the rest of the design quickly to get the painful part over with.

“Now you,” Magnus tells him, his pupils blown impossibly wide as he struggles to get his breathing back to normal.

Alec nods and positions the stele over his own wrist, making quick work of drawing the second part of the rune into his skin. As soon as he finishes the last curve, the rune lights up, pulling a shocked sound from him and Magnus both.

“Oh, Lord,” Magnus says, slumping forward and getting both hands on Alec’s arms to steady himself. “That is—”

“I can feel your magic,” Alec replies, his fingers curling into tight fists as he focuses on keeping himself together. “It’s  _ inside _ me. Not like before—it’s not  _ with _ me, in me—but it’s there, and I can  _ feel _ it, Magnus, I can— _ by the angel _ …”

He tilts his head back, a ragged cry leaving his throat as the magic inside him reaches a breaking point. He lets go of Magnus and throws his arms out wide, feeling magic soar through him, spilling from his fingers, his toes, the top of his head, his  _ eyes— _

“Breathe,” Magnus tells him, a hand coming up to cup Alec’s face, fingers stroking gently across his cheekbone. “Just breathe, Alec. Pull the magic back in. Focus it until you can hold it in your hands. There you go, darling; you can do it.”

His voice cuts through the haze of magic and gives Alec a firm point to focus on. He pulls himself together and starts pulling at the magic, getting a feel for how it moves through him and how he, himself can change its direction.

It takes him a few minutes, but he gets there in the end, the warlock magic Magnus is sharing with him through their new rune concentrated into a swirling, green orb in Alec’s right hand.

“You’re beyond mortal description,” Magnus breathes out, before he reaches out and forms a blue orb of his own, slowly letting it move closer to the one Alec’s holding.

The colours touch, and then slowly start to overlap. Alec throws out his free hand, reaching for Magnus to get himself grounded again. Getting to wield Magnus’ magic is already humbling in the extreme, but to feel it right there alongside him, it’s—Alec blinks furiously, trying to clear his eyes.

“I love you,” he manages, and then feels another wave of magic roll through him as Magnus lets his own essence fully merge with the part of it that Alec is currently wielding. “Don’t ever let me go, please, Magnus. I never want to live another day without you by my side.”

“ _ Never _ ,” Magnus promises fervently, and even more magic flows through Alec’s body and mind, leaving him feeling achingly vulnerable and impossibly powerful, all at once.

“Okay,” he says, after he finally manages to pull himself away from Magnus’ touch and put out the glowing orb that’s hovering in his palm, “now, you try to activate it. Let’s see what you can do.”

“Okay,” Magnus echoes. He moves back a few paces and holds up this wrist, snapping the fingers on his free hand to call on his magic and letting it sweep along the lines of the rune.

The rune lights up, and Alec feels instantly revived, as though he just activated a few runes of his own.

“Whoa,” he exclaims, closing his eyes for a moment as the power flows through him. “That’s—”

“Sharing the power seems to augment it, yes,” Magnus fills in. “I felt it before, when you tried out my magic, and from the look on your face now, it definitely goes both ways.”

“Yeah, you can say that again,” Alec replies, a wide grin spreading across his face. “My entire skin feels like it’s buzzing.”

“I feel… light. Strong. As though I could run for miles without breaking a sweat,” Magnus says. He experimentally spins around on one foot, then jumps up high enough to brush the ceiling with his fingers, and comes back down into a crouch. A smile breaks on his face as he turns his head to look at Alec. “Hand me your seraph blade.”

Alec pulls the extra blade he’s carrying from the holster at his thigh and throws it to Magnus, then draws his bow and wills his quiver into existence. “There, now try to stop me without magic.”

He nocks an arrow without giving Magnus time to process his words, drawing the string of his bow back and letting the arrow fly. The seraph blade in Magnus’ hand lights up a brilliant white and blocks the hit without any discernable effort on Magnus’ part. Alec feels his smile widen as he lets a second arrow fly, than a third, a fourth, a fifth…

Magnus blocks his every move, the blade moving swiftly through the air, as though Magnus has been fighting with it for years. He deflects the last arrow Alec sends his way and then surges forward, forcing Alec to drop his bow in favour of pulling out the spare seraph knife he keeps at the side of his boot.

They come together, raining blows upon each other, blocking and dodging and spinning as they test out the limits of their new rune. At one moment, Alec finds himself pushed to his knees, Magnus bearing down on him with momentum and gravity both on his side.

A second later, bright blue light explodes from Alec’s hands, and Magnus staggers backwards, only just able to pull a shield up in time.

“This is amazing,” Alec declares, pushing the words out between breaths that are getting increasingly laboured. “You’re moving as well as any Shadowhunter at the Institute. Better than most of them, in fact.”

“You’re not half-bad, yourself,” Magnus replies, just as Alec sends a massive fireball in his direction. “Come on, try to take down my shield.”

Alec smiles and focuses inward, feeling the magic coming through from the rune build at his core. He grabs it with his mind and throws it outwards, feeling a surge of satisfaction as it crashes into Magnus’ shield charm and makes it flicker in and out of existence.

“ _ Very _ good,” Magnus remarks, letting the shield fall and lowering his borrowed seraph blade while he’s at it. “A little bit of training and you, my love, will be absolutely unstoppable.”

“So will you,” Alec replies. “Not that you weren’t already.”

Magnus laughs. “Flattery will get you everywhere. Now, do you want to call Clary and report our findings, or shall I?”

“I don’t know. What’s in it for me if I do?”

“Me, in our bed, all slicked up and waiting for you,” Magnus replies with a grin, which widens when his words make Alec lose his breath for a second. “Unless you’d rather I call her? Give you a few minutes to  _ gather your wits _ ?”

Desire starts burning anew in Alec’s gut—never really stopped, to be honest. He wets his lips, doing his best to ignore the way his cock is suddenly far too interested in the proceedings, filling out and starting to press insistently against his fly.

“Um. Yeah, I, uh—why don’t you call her?” he manages, feeling his face flush as Magnus’ pupils darken with want. “I’ll—you know where to find me.”

He practically sprints towards his and Magnus’ bedroom, stopping himself once he gets through the door and then forcing himself to keep the trembling to a minimum as he removes the rest of his clothes and gets into bed.

The bottle of lube is in the drawer of the bedside table on Magnus’ side, like always, and Alec breathes a sigh of relief as he coats his fingers and brings them down in between his legs, taking a few moments to stroke his cock before venturing lower.

He’s up to three fingers and starting to properly fuck himself down on them when Magnus enters the room, moving over to the side of the bed and quickly ridding himself of his own clothes. Once he’s naked, he lies down next to Alec and pops his head up on one arm, placing the other on Alec’s chest. He lowers his head and starts pressing a line of kisses down Alec’s throat, and the hand on Alec’s chest strokes a path down his side to his thigh, pulling it up and to the side, to give himself a better view.

“There are so many things I want to try,” Magnus murmurs. “Been wanting to have you like this for so long now.”

Alec nods fervently in agreement, and then brings his free hand up to cup the back of Magnus’ neck and pull him in for a deep kiss. The Alliance Rune has gone mostly quiet by now, but the newly-connected bond between them is out in full force, Magnus’ magic flowing into Alec wherever their bodies touch, joining with Alec’s own essence and letting it flow back into Magnus in return. 

He can feel the stuttering, excited rhythm of Magnus’ heart as though it is his own, speeding up as their kisses grow more and more involved.

“Need you inside of me,” Alec tells him, his words cut off by a hoarse moan as Magnus strokes his hand down his abs, little sparks of magic soaking into Alec’s skin and going straight to his bloodstream. “Magnus,  _ please _ .”

Magnus claims his lips for another heated kiss, shifting their positions until he’s got Alec pressed into the mattress beneath him, their hips rocking together in quick, desperate grinds. He finds both of Alec’s wrists and guides them up above his head. Their fingers lock together, and Alec feels the bond between them like a live wire, running through their joined hands back into either bodies, setting off sparks of pleasure everywhere it passes through.

He pulls his knees up higher, tilting his hips up, feeling the hot, wet tip of Magnus’ cock drag across his rim. His fingers press into the backs of Magnus’ hands, his breathing growing quick and laboured.

“ _ Now _ .” 

He’s already slick and open from his own fingers, so Magnus follows his lead, moving himself into position and then slowly starting to push his cock inside. They both let out a moan as he bottoms out, and Alec is hit by a sudden, desperate need to push every bit of his energy through the bond and have it fill Magnus’ entire body, to try and give back some of the incredible feeling of having Magnus inside of him.

Magnus starts moving his hips in tiny, circular movements, staying fully buried inside of Alec as they breathe against each other’s lips. It’s intimate on a level Alec didn’t know existed; it goes beyond the love they already shared, painting every emotion Alec’s experienced before against a far more vivid, vibrant background. His soul is thrumming with the energy of their bond, similar, in a sense, to the surge of power through his  _ parabatai _ bond the middle of battle, but at the same time, so incredibly different from that.

The bond with Magnus doesn’t feel like two halves of a whole knitting themselves back together—it’s deeper and somehow far more all-encompassing than that. Magnus’ soul next to his makes Alec’s feel whole and perfect in and of itself; it makes him ache to share every bit of that perfection with Magnus—to lay himself completely bare, give himself over and receive everything that Magnus is in return.

His heart burns with the sudden certainty that all of that is actually going to happen; he’ll get to have Magnus with him.

In every way.

For the rest of his life. 

“I’m afraid this is going to be over a lot quicker than usual,” Magnus tells him breathlessly, his voice ending on an almost pained-sounding groan as Alec wraps his legs around him as best he’s able, pulling Magnus even deeper inside himself. “Sorry about that.”

“Don’t care,” Alec manages, arching into the next push of Magnus’ hips. “Just  _ move _ .”

Magnus swallows thickly, and then nods and catches Alec’s mouth in a searing kiss. His hips pick up a fast, hard rhythm, and a sense of almost desperate desire flows from him into Alec. Alec can feel his own body answer in kind, getting him from throbbing hard to teetering on the edge so fast, it makes him dizzy.

It’s all he can do to just lie back and let himself be taken along for the ride. With every thrust inside him, Magnus pushes them both closer and closer to orgasm, pleasure spiking through the connection every time they come together. Alec’s fingers are digging into the back of Magnus’ hands in a way that has to be outright painful, but he still can’t make himself ease up. He needs the bond like he needs the air he tries to drag into his lungs—and Magnus keeps answering in kind, desperate words of praise falling from his lips.

“Look at me,” Magnus urges, his breathing coming out in ragged pants. “When it breaks, push it all back into me.”

Alec doesn’t have time to ask what he means before pleasure veritably crashes into him. He lets go of Magnus’ hands and grabs hold of his shoulders to anchor himself, his head tipping back, and his lips parting in a hoarse shout as Magnus’ magic pours into him alongside his release, filling him up from deep inside his core all the way out to the very tips of his fingers.

The feeling grows inside of him, the pressure of it increasing until Alec thinks he can’t possibly take it anymore. The magic is pulsing within him, far too big and wonderful to be contained, and Alec cries out again and again as wave after wave of it continue to roll through him.

“Alec,  _ please _ ,” Magnus pants, right next to his ear, sounding more wrecked than Alec’s ever heard him. His words end on a moan that sounds like it’s equal parts pleasure and pain, and Alec tries to pull his scrambled brain back together and remember what it is he’s supposed to be doing.

He comes up empty, another wave of pleasure washing over him as Magnus keeps moving his hips, keeps fucking into Alec like he can’t bear for them to stop. Alec surges up and catches Magnus’ lips in a hard kiss, desperately drinking down the choked off moans Magnus makes as his whole body shudders.

“What do you need?” he finally manages, tearing his lips away to press his whole body closer to Magnus’. “Whatever it is, take it. It’s all yours.  _ I’m _ all—”

His voice breaks as he feels a pulling sensation start in his hands, then travel quickly up the length of his arms. He arches his back, pressing himself as close to Magnus as he possibly can, and it’s suddenly blindingly clear, what Magnus is asking for.   

He opens his eyes, blinking several times to clear the hot, burning sensation in them and meets Magnus’ golden ones. He focuses inward, mentally grabs the overwhelming pressure of magic that’s threatening to crack him open, and starts pushing it back, making strands of magic flow towards his arms and into his fingers, letting them soak back into Magnus’ skin.

“ _ Oh, God, _ ” Magnus moans, his eyes rolling back in his head and his mouth falling open as an expression of pure bliss overtakes his face. “ _ Alexander _ .”

“I’m here,” Alec answers, tightening his legs around Magnus and rolling them over to their sides as tremors begin to run all along Magnus’ body. “Just lean back and let me take care of you.”

“Love the way you feel,” Magnus mumbles, his eyes falling shut again as he loses himself to the pleasure of Alec’s hands. “Like dewy grass in the middle of summer…”

Alec feels himself smile at the comparison. He shifts his weight again, pushing himself up so that he can straddle Magnus’ thighs, and then starts working the magic back into him in earnest, loving the way Magnus moves beneath him—every breathless sound he makes. Magnus’ magic keeps surging up towards him, bathing Magnus’ skin in brilliant blues wherever Alec’s fingers touch.

Magnus cries out again, as Alec strokes his right hand down his sternum, fingers drawing teasing spirals until he’s got his palm resting right above Magnus’ pelvic bone.

“Alec, please—”

Alec lets his hand move lower, foregoing any teasing he might have been contemplating in response to the pure, raw need he can hear in Magnus’ voice.

“ _ Hey _ . Hey, Magnus, just let go. I’ve got you.”

He wraps his hand around the base of Magnus’ erection, unable to hold back a gasp as the sparks of magic follow his touch. Magnus’ hips move into his grip in erratic little pushes, his cock still hard, despite his earlier release.

“I love you so much,” Alec murmurs, leaning forward to catch Magnus’ lips in a slow kiss, working his hands between their bodies, stroking Magnus’ magic back into his body with even, tight twists of his wrist.

Magnus moans into his mouth, and moments later, Alec feels the pressure of Magnus’ magic that’s still building beneath his skin leave him in a blinding rush, flowing back into Magnus and leaving them both panting for breath as they ride out the pleasure in each other’s arms.

“Oh wow,” Alec says, once he’s managed to roll to the side and wet his lips. His heart is still beating wildly, and even though it’s been pushed to the background, he can still feel Magnus’ magic like a steady, grounding pulse, deep inside his chest. “Magnus, that was—”  

“Yeah,” is Magnus’ only reply, and the pure wonder in his voice makes Alec feel awed and humbled all over again. He pulls Magnus closer, turning to his side and putting his free arm around him as well.

“I don’t know how to do this,” he confesses, tightening his grip as he feels Magnus begin to stiffen against him. “No! No, not like that. I just—I can feel you  _ everywhere _ . It’s amazing. It’s—”

“Absolutely terrifying,” Magnus says, taking the words right out of Alec’s mouth. And then he tilts his head up, looking back at Alec with unglamored eyes. “But I’m willing to take the jump, if you are?”

“I am,” Alec replies, immediately, his left hand going to Magnus’ face, cradling it in his palm. “Magnus, I love you. More than I ever thought possible.”

“I love you too,” Magnus replies, the corner of his lips tilting upwards before he leans in to catch Alec’s mouth in a long, slow kiss. His hand comes up to tangle in Alec’s hair, and Alec can’t hold back a small moan as he leans into the touch, letting Magnus take full control of their kiss.

“You’re my first of so many things, Alexander Lightwood,” Magnus murmurs against his lips, and Alec feels the smile as it brushes against his skin, drawing out one from himself as well. “And I think you might be my last of quite a few things, as well.”

The words hit a bittersweet cord in Alec—elation, pride and pure happiness warring with the helpless feeling that always comes with a mention of Magnus’ immortality. He pulls Magnus closer against him, parting his lips and deepening their kiss in the hope that Magnus will be able to read everything he’s feeling through their connection, instead of the words he can’t quite find.

From the way Magnus’ smile widens and he melts into their kiss, he thinks he’s doing quite a good job of it. They kiss until the sparks of magic around them flicker our and their heartbeats match each other and settle into something regular and calm that leaves them both smiling, foreheads pressed together as they bask in the afterglow.

“I can’t believe I’ll get to marry you,” Alec whispers, a happy thrill going through him when he feels Magnus’ heart speed up a little at the words. “You’re absolutely amazing.”

“I could say the same thing about you,” Magnus replies, and then reaches up, pressing a kiss to the tip of Alec’s nose and making them both laugh. “So, what do you think? Should we stay in bed for the rest of the night or actually get up and make dinner?”

“Definitely stay in bed,” Alec replies, stretching out his legs beneath the blanket. “And then tomorrow, you sleep in, and I’ll make us breakfast.”

The smile on Magnus’ lips widens. “Oh, I  _ like _ the sound of that. Waffles?”

“What else?”

“Sounds like I should get engaged more often,” Magnus teases. “If it gets me waffles in bed.”

“Good idea,” Alec replies, tilting his head to catch Magnus’ lips in another kiss. “How does every weekend for the rest of our lives sound?”

Magnus leans into the kiss, parting his lips to make it deep, thorough and utterly dizzying. “Absolutely perfect.”

“Yeah?”

“Mm-hmm”

Alec feels a laugh work itself past his lips, into Magnus’ mouth. “I really need to go clean up, but I can’t stop kissing you.”

Magnus chuckles, and then catches Alec’s lower lip teasingly between his teeth. “I don’t mind a little bit of a mess.”

“You’re terrible,” Alec huffs, pressing yet another kiss against Magnus’ lips before tearing himself away. “You’re the one who’s always complaining about stains on the sheets. I’m trying to be responsible here.”

“And you’re doing it  _ so well _ ,” Magnus agrees, his sentiment rather negated by the fact that he’s still smiling widely and pressing kisses to whatever part of Alec’s face and neck that he can reach. Then he holds out his hand, and Alec’s stele flies into it. “Care to give that Alliance Rune another go? See if you can figure out how to do a cleaning spell?”

Alec laughs and takes the stele from him, making it light up as he moves it to his wrist. “I like a challenge.”

“Then show me your moves, Shadowhunter,” Magnus says, a small smirk curling the corner of his mouth as he rolls over on his side, propping his head up on one hand. “I’m ready to be dazzled.”

Alec rolls his eyes and does as told. This time, when Magnus’ magic surges through him, he’s ready for it, finding his focus and reining it in before it has time to take him over completely.

He leans over and takes Magnus’ hand in his, feeling the bond between them start to hum with energy again. It gives another dimension to the power granted him by the rune, and one that Alec is willing to bet will make a huge difference on the battlefield.

Valentine and his army won’t stand a chance.

He calls on his borrowed magic and snaps his fingers, the same way Magnus does. A gust of wind runs through the room, raising the hairs on Alec’s arms and making him shudder from cold. He looks down; the growing wet spot is still there, but he’s somehow managed to make the sheets change colour.

“Not a word,” he tells Magnus, who has rolled over and buried his face in the—no longer dark blue, but emerald green—pillows, trying and failing to hide his laughter.

“Wouldn’t dream of it,” Magnus replies, once he comes back up for air. “Try again?”

Alec huffs and closes his eyes, focusing hard to direct the magic. This time, he gets it more or less right.

“I did it!”

“Good job, Alexander,” Magnus agrees. Something flickers in his eyes, and the next thing Alec knows, he’s flat on his back on the bed again, his body arching into the touch by instinct as Magnus’ mouth comes down on his skin and starts kissing a wet path down his stomach.

“You missed a spot,” he says, his gaze dark and glittering once he looks back up and meets Alec’s eyes. “Maybe you should practice some more?”

“Yeah. Yeah, good idea,” Alec replies, his breathing laboured as he reaches for Magnus, pulling him up the bed and rolling them over so he comes down on top of him. “Let’s do that right now.”

Magnus is still laughing when Alec kisses him.

It’s the best feeling in the world.

**Author's Note:**

> Comments are love. <33333
> 
> Come yell about Shadowhunters with me on [tumblr](http://actuallyredorchid.tumblr.com/)!


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